Thermoplastic resins and thermosetting resins made of polymer materials have been widely used in the industrial field, and are generally required to have characteristics such as heat resistance and toughness. These characteristics of polymer materials are generally dependent on the glass transition temperature (Tg), and the determination of Tg values of various polymer materials has a great significance in terms of the design and production of industrial products. Conventionally, the Tg of a polymer material has been determined based on the differential scanning calorimetry (DSC).
Recently, development of high performance materials by complexing a polymer and an inorganic filler has been active. Since the decrease in size and improvement in dispersibility of the inorganic filler lead to a remarkable increase in area of the interface between the polymer and the inorganic material, the physical properties at the interface may determine the physical properties of the material as a whole. Accordingly, the understanding of the thermal mobility of molecular chains at an interface with an inorganic material is an important issue to be studied.
The fluorescent probe method is widely known as an approach for investigating the dynamic environment of a matrix polymer by evaluating the fluorescence intensity, the fluorescence lifetime, and the rotational relaxation time as functions of the temperature (see, for example, Non-Patent Document 1). It is also known that, if probe molecules can be arranged with positional selectivity, the fluorescent probe method is extremely useful as an approach for space-resolved evaluation of the Tg in a confined space such as a thin film or an interface with another kind of solid (see, for example, Non-Patent Documents 2 and 3). Until now, it has been revealed that the Tg of polystyrene (PS) at an interface with an inorganic solid is remarkably higher than the bulk value based on an evanescent wave excitation fluorescence lifetime measurement (see, for example, Non-Patent Document 2).